Monday, April 1, 2013

Biomimicry: From Termites to Towers

Almost
everyone on the planet has had their life improved by biomimicry,
“the design of production of materials, structures, and systems
that are modeled on biological entities and processes.” (Oxford
Dictionary). Another way of describing biomimicry would be
technology by man inspired by nature. There's good reason to look
toward biomimicry; billions of years of evolution have lead to many
examples of complex diversity in nature. Many sustainable
technologies & products have been created because of people
examining nature's existing efficiency, with a broad range that
includes passive cooling technology inspired by termites, whale
powered wind turbines, gecko infused tape and, most easily
recognizable due to it's many uses and longevity, Velcro.

Velcro
was designed in 1941 & patented in 1955 by Swiss electrical
engineer & hunting enthusiast George de Mestal (Hall of fame
inventor Profile). De Mestral's imagination was sparked by returning
home from a hunting trip one day & examining the recently plucked
burrs that stuck to his jacket & his dogs fur (Gregory). Burrs,
which are generally attached to a seed or dry fruit, have hooks as
both a means to protect the plant from herbivores & also as a
means of seed dispersal. De
Mestral took some of the burs and examined them under a microscope.
What he saw was hook-like seeds meshed with hooped fibers gripping
and fastening to each other. De Mestral considered that the adhesive
qualities of plants with burrs could be useful when applied to
everyday life, an example of biomimicry in action.

It's
somewhat ironic that de Mestral was inspired by a part of a plant in
nature that was, until that point, only an annoyance for humans. It
turns out the inventor was also as tenacious as the burrs themselves;
his idea did not win over investors after it's inception. Another
ironic spot in the life of de Mestral considering he received his
first patent at the age of 12 only to be “severely” & “openly
laughed at” (Thomas) when he initially pitches his greatest idea
yet.

After three years
of work de Mestral finally had his initial design completed: two
lineal cotton fabric strips, or round squares, sewn or adhered to
opposite sides. The first fabric strip had 300 hooks per square inch
and the second fabric strip had 300 loops per square inch (Thomas).
The initial design worked by not as effectively due to being made of
cotton.

Cotton
is a fluffy fiber that grows around seeds of a shrub plant from a
genus called Gossypium. The fiber is around 90% cellulose which is a
polysaccharide (long string of carbohydrate molecules joined
together) comprised mostly of glucose. Cotton is spun into a yarn and
is then turned into a flatter material. After this refinement the
cotton is still fluffy and proved to be a poor material to create
what would become Velcro. Eventually de Mestral discovered that he
could create the texture needed by sewing nylon under an ultra violet
light, causing the material to be both burned & sewn into the
shape (Strauss). After a couple years of production de Mestral was
producing over sixty million yards of Velcro per year. Today it's an
everyday item capable of supporting 175 pounds per two square inches
(Freeman) & is used in items ranging from pen holders to
automobiles.

Aristotle
has one of the earliest recorded comments about biomimicry,
commenting on how the Gecko can “run up and down a tree in any
way.” (Aristotle) One wonders what the philosopher would think of
modern times: recently a product has become available that harnesses
the gripping power of a Gecko's setae (small hair-life structures on
the foot of a Gecko) called Gecko Tape. Gecko Tape is made with
synthetic setea that emulates a Gecko's setae. It was developed
between a collaboration of the Manchester Center for Mesoscience and
Nanotechnology and the Institute for Microelectronics Technology in
Russia in 2001 after two year’s of research (Nature). The research
yielded a product that is powerful but still not as strong as the
feet of a Gecko. It turns out that little reptilian feet are
complex.

A gecko's foot has toe pads consisting of about a half
million setae made of keratine (a fibrous structural protein) and
each one of these has fine hairs with hundreds of small projections
called “spatulae” on a nanoscale at their ends (Nature). Robert
Full from the University of California was the first to discover that
the adhesion from Gecko feet was due to Van der Waals forces created
between the spatulae and the surface. Van der Waals forces are
“intermolecular forces created by induced polarization of
molecules” which “become significant on the micro and nanoscale.”
(Nature) But the mighty foot of the Gecko continues to hold
mysteries: Andre Grim, credited with being the father of synthesized
setae, found that capillary forces also aided with the Gecko's
adhesive ability. Capillary forces are “attractive forces created
by the surface tension of a molecular layer of absorbed water that
forms between two surfaces” (Nature). This lead to the development
of nanotubes of synthetic Gecko foot hair, which when applied to the
old synthetic satae formula creates a formula that could be
potentially stronger than the properties of a regular Gecko foot. At
the moment each hair has “the same adhesive force as a single gecko
setae.” (Shah).

Design cues from
mother nature don't just manifest as accidental inspiration for
alternatives to zippers or a better sticking roll of tape. Biomimicry
has also been used by architects to create more efficient sources of
energy.

WhalePower produces
giant blades for wind turbines as an alternate form of energy.
Already commercially available, WhalePower has an advantage over
other wind turbine designs; it's modeled after the “fluid dynamics
and biomechanics” (The Science | Whalepower) of a humpback whale
flippers.

Nature has given
the humpback whale a very efficient flipper. They provide lift and
reduce drag, channeling flow and increasing aerodynamic efficiency
due to tubercles (a round node in the bone or skin). When tubercles
are in human lungs we call this tuberculosis, however when they are
on the edge of humpback whale flippers they are called innovative. By
replicating the texture of the tubercles on humpback whale flippers
designers for WhalePower were able to craft a more efficient wind
turbine. Wind tunnel tests have shown that models of blades designed
with humpback whale tubercles, instead of smooth surface blades,
offer full dynamic improvements including a “32% reduction in drag,
8% improvement in lift, and a 40% increase in angle of attack of
smooth flippers before stalling.” (Fish) WhalePower is extending
this technology to hydroelectric turbines, irrigation pumps &
ventilation fans.

In
Harare, Zimbabwe, architects have looked toward termites as a way to
discover new building techniques. Termite mounds in Africa can rise
to heights of over thirty feet. To compare to a man made structure
that would be equal to a human erecting a building 2,743 feet high
(Steinu). These mounds have complex systems such as ventilation tubes
and tunnels that continue up to 200 feet underground. When comparing
this to human structures the termite structures are much larger. The
architects on the Eastgate Centre building in Harare know this,
that's why they are developing their high-rise buildings with a
design modeled after termite ventilation systems to maintain a
consistent temperature in their structures. These buildings, designed
under biomimicry principles, use no conventional air-conditioning or
heating yet stays regulated “year round with dramatically less
energy consumption using designed methods inspired by indigenous
Zimbabwean masonry and the self-cooling mounds of African Termites”
(Fahrenbacher).

Termites in
Zimbabwe feed on a specific type of fungus that must be regulated at
exactly 87 degrees Fahrenheit. This is quite the job for the small
termites as temperatures outside range from 35 degrees to 104 degrees
(Fahrenbacher). The termites regulate the mound by opening and
closing a series of heating and cooling vents. By digging new vents
and plugging old ones the termites are able to keep the fungus at its
appropriate temperature & enjoy a constant source of food.

The ventilation
system designed by termites is essential to the Eastgate Centre
high-rise tower design. Outside air is warmed or cooled by the
building mass itself which is determined by checking the temperature
of the concrete and the air. Air is continually drawing in by large
open spaces and fans on the first floor. Fresh air replaces stale air
and exits through ports in the ceiling of each floor. By doing this
structures end up using 10% less energy of conventional buildings of
its size, which has trickled directly to residents; rent is up to 20%
lower than the surrounding buildings of Eastgate Centre.

Humans have a
tendency to take things in nature and give it a human element. Many
times this makes something more accessible for the better of
humanity. For example, taking many randomly shaped stones and
refining it into a protective structure in a shape of a square.
Biomimicry is placed in a reversed but also welcoming context: it's
technology for us all, inspired by nature, to make objects with a
human element more efficient for humans. Biomimicry will continue to
improve the work of architects, scientists, designers, artists and
the rest of the world.

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